This invention relates to a method and apparatus for starting a spinning machine, in which a yarn ending is carried out onto a spinning rotor before the speed of the latter reaches its steady speed.
Generally, in an open end spinning machine such, for example, as described in U.S. Pat. No. 3,354,626, each spinning unit includes means for feeding individually opened fibers into a spinning rotor, in which subatmospheric pressure is produced by rotation thereof. The opened fibers are formed into a yarn in the spinning rotor. The yarn is transported from the spinning rotor by take-up means including a yarn take-up tube and yarn take-up rollers and wound on a bobbin by winding means. Also, in the above open end spinning machine, each of the fiber feeding means, yarn take-up means and yarn winding means is mounted on a separate driving shaft and a single motor drives these separate driving shafts through a rotation transmission mechanism including trains of gears. This motor also drives an endless belt, which is in frictional contact with spindles of the spinning rotors to rotate the same.
When the spinning machine is stopped, the fiber feeding means, yarn take-up means, yarn widning means and endless belt are simultaneously stopped, which causes breaking of the yarn simultaneously in all the spinning rotors. At that time, the yarn end remains in the yarn take-up tube, i.e., in the region which undergoes the suction effect of the subatmospheric pressure produced in the spinning rotor when the spinning machine is in operation, and the fibers remain in the spinning rotor.
To start the spinning machine, rotation of all spinning rotors is simultaneously started, whereupon the yarn take-up rollers are rotated in a reverse direction to push the yarn ends from the take-up tubes into the spinning rotors and the remaining fibers are re-collected in fiber collecting grooves formed in the spinning rotors and twisted into the yarn ends. Thus, a yarn ending is completed in each spinning rotor. In order to facilitate the yarn ending by increasing a time tolerance for a proper timing of the rearward feeding of the yarn end in reference to the supply of new fibers, the yarn ending has been effected while the speed of the spinning rotor is still in the lower level, in which the speed is lower than the steady speed of the spinning rotor during the normal spinning operation.
With this starting method, the remianing fibers in the spinning rotor are not satisfactorily collected because of the lower speed of the spinning rotor during the yarn ending operation and therefore the yarn end can not be properly connected with the collected fibers, resulting in a reduced success rate of the yarn ending and production of an irregular yarn. Especially, in the case where the spinning rotor is of the air self-discharging type in which air is discharged from the interior of the spinning rotor through openings formed in the bottom thereof thereby to provide a subatmospheric pressure in the spinning rotor, the amount of air discharged from the latter is greatly reduced during rotation of the spinning rotor at a lower speed so that the yarn end in the yarn take-up tube communicating with the spinning rotor can not be stretched out sufficiently to prevent the occurrence of snarls at the yarn end. The snarls of the yarn end have an adverse affect on the rearward feeding of the yarn end, resulting in a reduced success rate of the yarn ending.
It is therefore a principal object of this invention to provide a method and apparatus for starting a spinning machine, which can remove the above-discussed disadvantages of the prior art.